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  • Author: M.A. Alam x
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Transient Heat and Mass Transfer Flow through Salt Water in an Ocean by Inclined Angle

Abstract

In the present computational study, the inclined angle effect of unsteady heat and mass transfer flow through salt water in an ocean was studied. The governing equations together with continuity, momentum, salinity and temperature were developed using the boundary layer approximation. Cartesian coordinate system was introduced to interpret the physical model where x-axis chosen along the direction of salt water flow and y-axis is inclined to x-axis. Two angle of inclination was considered such as 90° and 120°. The time dependent governing equations under the initial and boundary conditions were than transformed into the dimensionless form. A numerical solution approach so-called explicit finite difference method (EFDM) was employed to solve the obtained dimensionless equations. Different physical parameter was found in the model such as Prandtl number, Modified Prandtl number, Grashof number, Heat source parameter and Soret number. A stability and convergence analysis was developed in this study to describe the aspects of the finite difference scheme and this analysis is significant due to accuracy of the EFDM approach. The convergence criteria were observed to be in terms of dimensionless parameter as Pr ≥ 0.0128 and Ps ≥ 0.016. The distributions of the temperature and salinity profiles of salt water flow over different time steps were investigated for the effect of different dimensionless parameters and shown graphically.

Open access
Yield Potentiality of Maize as Relay Crop with T. Aman Rice under Different Agronomic Management

Abstract

The experiment was conducted at the Regional Agricultural Research Station, BARI, Ishwardi, Pabna, Bangladesh, during 2013-2014 and 2014-2015 to introduce maize as relay crop with T. Aman rice under different agronomic practices for determine the production potentials. The experiment was design split plot with three replications. The agronomic management practices included four plant spacing viz. S1=75 cm×20 cm (66666 plants/ha), S2=60 cm×20 cm (83333 plants/ha), S3=50 cm×20 cm (100000 plants/ha) and S4=40 cm×20 cm (125000 plants/ha) and four soil management practices viz. M1=soil mulching at 25 DAE, M2=earthing up at 25 DAE, M3=straw mulching at 25 DAE and M4= without earthing up and mulching (control). Seeds were relayed by dibbling manually in 10 days before the harvest of T. Aman rice. Results showed that an increasing plant spacing increased leaf area Index (LAI), total dry matter (TDM), crop growth rate (CGR) and light energy interception (LEI). Grain yield was higher in S3 spacing (8.44 t/ha) than others (S4 8.11 t/ha, S2 7.34 t/ha and S1 6.89 t/ha). Among the soil management practices, M2 increased LAI, TDM, CGR, LEI as well as grain yield. Moreover, M2 and M1 gave similar grain yield (8.22 t/ha and 8.02 t/ha), that were significantly greater than other two soil management practices (M3 7.55 t/ha and M4 6.98 t/ha). From the economic point of view, combination of S3M1 gave better performance with gross margin of Tk. 95000/ha and BCR of 2.17. On the basis of results, S3M1 combination was suitable for growing maize under relay sowing with T. Aman rice.

Open access
Foliar Nitrogen Management for Improving Growth and Yield of Dryland Wheat

Abstract

Foliar nitrogen (N) application is considered an important factor affecting phenology, growth, yield, and yield components of dryland wheat (Triticum aestivum L.). A field experiment was conducted to study effects of foliar N on dryland wheat (cv. Prisabk-2004) at the Agronomy Research Farm, The University of Agriculture Peshawar, Pakistan, during winter 2010-2011. The experiment was laid out in randomized complete block design using four replications. A plot size of 3 m by 4 m, having 8 rows, 4 m long and 30 cm apart was used. A total of 80 kg N ha−1 in the form of urea was applied. Out of 80 kg N ha−1, 70 kg N ha−1 was applied to the soil at sowing time, and the remaining 10 kg N ha−1 was applied in the form of foliar spray (2% N). The required foliar N was applied in various combinations (splits) at different growth stages viz. 30, 60, 90 and 120 days after emergence (DAE). Phenological development (days to anthesis and physiological maturity) was delayed, yield components and yield increased significantly (p ≤ 0.05) with foliar N over control (water spray without N). Wheat grain yield increased to the highest level (4427 kg ha−1) when 100 % foliar N was applied (no split) at 90 DAE, followed by 4050 kg ha−1 at 120 DAE, while the control (no foliar N) resulted in the lowest grain yield (2573 kg ha−1). We concluded from this study that 2 % foliar N application in a single split either at 90 or 120 DAE could improve wheat productivity under dryland condition.

Open access
Morphological characterization of garlic (Allium sativum L.) germplasm

Abstract

A total of 25 garlic (Allium sativum L.) germplasm were collected from different location of Bangladesh and also from different countries of the world. Each germplasm was planted in each plot of 1m2 at the Allium Field Laboratory, Horticulture Farm, Bangladesh Agricultural University, Mymensingh. This study was conducted during October, 2010 to March, 2011 in the field, using randomized complete block design with three replications. All germplasm were characterized on number of leaves, height of plant, leaf length, fresh weight of leaf, dry weight of leaf, number of cloves per bulb, length and diameter of bulb, fresh weight of bulb, dry weight of bulb, yield per plot and yield per hectare. Analyses of variances showed that garlic germplasm with different origins were significantly different for all characters. Different germplasm resulted better performances but germplasm G49 from Vietnam gave the highest results in respect of number of leaves per plant (10.63), leaf length (43.57 cm), fresh leaf weight (92.47g), dry leaf weight (6.13g), fresh weight of bulb (21.37g), total number of cloves per bulb (42.13), bulb diameter (4.13cm), fresh weight of bulb (21.37g), dry weight of bulb (5.73g) and yield (9.83 t/ha) which could help future researchers in garlic selection program and improvement of yield.

Open access
Effect of Storage Containers and Lengths of Storage on the Germination, Moisture Content and Pest Infestation of Wheat Seed

Abstract

A laboratory experiment was conducted at the Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Dianjpur-5200, Bangladesh to evaluate the storage containers and duration of seed storage on the germinability and health of wheat seeds. The experiment was carried out in two factors, viz. three storage containers naming i) sealed tin container, ii) plastic container, iii) gunny bag, and four storage periods of i) 15 days, ii) 30 days, iii) 45 days, and iv) 60 days. Completely randomized design (CRD) was used in this experiment with eight replications. The results revealed that the germination percentages (GP) of the seeds stored in the gunny bag decreased quickly from 66.1 to 32.8% due to contained with high moisture content in seed. But, slowly decreasing trends of GP from 80.4% to 69.2% was observed in the sealed tin container seeds with lesser moisture content than that of gunny bag and plastic container. The reduction of GP was so higher of 50.38% in the seeds contained in gunny bag than that of only 13.93% in the seeds contained sealed tin container. Wheat seeds stored in sealed tin container, plastic container and gunny bag significantly increased moisture content in ambient condition for 60 DAS. The moisture content of the seeds stored in gunny bag was found to rise remarkably more than other containers. This escalation of seed moisture content was closely related to the surrounding environmental conditions, like temperature and relative humidity where seeds were stored. The rate seed deterioration in gunny bag and plastic container paralleled the level of invasion by storage insect was found. During storage period, insect infected the seeds, and the insect bitten seeds were also found higher in gunny bag and plastic container, but lower in sealed container. Wheat seeds should be stored in air tight sealed container and drying should be done after some days of storage (45-60 DAS).

Open access
MHD boundary layer flow and heat transfer characteristics of a nanofluid over a stretching sheet

Abstract

The study of radiative heat transfer in a nanofluid with the influence of magnetic field over a stretching surface is investigated numerically. Physical mechanisms responsible for magnetic parameter, radiation parameter between the nanoparticles and the base fluid, such as Brownian motion and thermophoresis, are accounted for in the model. The parameters for Prandtl number Pr, Eckert number Ec, Lewis number Le, stretching parameter b/a and constant parameter m are examined. The governing partial differential equations were converted into nonlinear ordinary differential equations by using a suitable similarity transformation, which are solved numerically using the Nactsheim-Swigert shooting technique together with Runge-Kutta six order iteration scheme. The accuracy of the numerical method is tested by performing various comparisons with previously published work and the results are found to be in excellent agreement. Numerical results for velocity, temperature and concentration distributions as well as skin-friction coefficient, Nusselt number and Sherwood number are discussed at the sheet for various values of physical parameters.

Open access
Catha Edulis Active Principle, Cathinone, Suppresses Motor Coordination, Accelerates Anxiety and Alters the Levels of Dopamine and its Metabolites in the Limbic Areas of Male Swiss Albino Mice

Abstract

Cathinone, the active principle of khat (Catha edulis), stimulates, excites and produces euphoric feelings in khat users. Locomotor and rearing activities, either individual or in groups, of male Swiss albino mice were decreased significantly compared to the control. Motor coordination tests (rotarod, rope climb and grip tests) have shown decreased motor performance in the mice treated with cathinone compared to the control. The elevated plus maze test has shown significant anxiety in the mice compared to the control. Contents of dopamine and its metabolite, homovanillic acid, were increased in the limbic areas compared to the control group. In contrast, contents of 3,4-dihydroxyphenyl acetic acid were depleted significantly and dose dependently compared to the control group in the limbic areas of mice. In conclusion, natural cathinone has depleted motor coordination, accelerated anxiety in mice and altered the contents of dopamine and its metabolites.

Open access